1. The Field of the Invention
The present invention relates to a connector for joining plastic tubes.
2. The Relevant Technology
In particular, the present invention relates to a connector comprising a body having a throughway which is open at one end, a shoulder in the throughway which faces the open end and supports an O-ring; a collet in the open end of the throughway and having a plurality of legs extending away from the open end, each engaging with the body and having an inwardly facing tooth to grip, in use, a tube in the throughway. Such a connector will subsequently be described as “of the kind described”.
Connectors of the kind described have found widespread use in applications for connecting plastic tubes and the like, for example, in plumbing, electrical cables and fibre optic applications. They provide a quick and reliable method of joining two cables together or connecting a cable to another component.
A conventional connector of the kind described has a two-part body assembly. This consists of a body which is provided with the internal features such as the shoulder described above and a cap which is fitted over the body and is ultrasonically welded in place. This is necessary as the profile of the body cannot readily be moulded in a single piece.
While the ultrasonically welded cap has a number of advantages and has proved commercially successful, it does have a number of drawbacks. The welding process requires complex equipment. The materials of the cap and body must be compatible with one another and suitable for ultrasonic welding, and the cap and the body must be sufficiently thick and robust to allow the welding.
In an attempt to address these problems, it has been proposed (for example in the John Guest 3 mm Miniature Straight Connector, Product #DS-NC2129) that the end of the cap opposite to the open end is provided with an inwardly facing annular shoulder which is snap fitted over a complimentary outwardly facing annular shoulder on the body.
This overcomes the above problems with ultrasonic welding. However, it introduces problems of its own. The snap ring on the cap has to expand radially outwardly as it is pushed into the body. This puts considerable strain on the cap which can lead to cracking. Also, as the annular snap ring snaps into place behind the shoulder on the body, this snapping into place can actually cause impact cracking.
Further, when in situ if a bending load is applied to the connector, the bending force is such that it tends to pull the snap ring away from the shoulder on one side, while on the opposite side, the snap ring can be forced towards the shoulder, these stresses can cause the cap to crack or become dislodged from the body.